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<head><meta charset="utf-8"><title>Universes · t-compiler · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/index.html">t-compiler</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Universes.html">Universes</a></h3>

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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Universes/near/154514460" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Matthew Jasper <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Universes.html#154514460">(Jan 06 2019 at 12:37)</a>:</h4>
<p><span class="user-mention" data-user-id="116009">@nikomatsakis</span> What's the expected behaviour for the examples here: <a href="https://play.rust-lang.org/?version=nightly&amp;mode=debug&amp;edition=2018&amp;gist=e598eb97e155c66c710959b52ae8e765" target="_blank" title="https://play.rust-lang.org/?version=nightly&amp;mode=debug&amp;edition=2018&amp;gist=e598eb97e155c66c710959b52ae8e765">https://play.rust-lang.org/?version=nightly&amp;mode=debug&amp;edition=2018&amp;gist=e598eb97e155c66c710959b52ae8e765</a></p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Universes/near/154578185" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Universes.html#154578185">(Jan 07 2019 at 15:47)</a>:</h4>
<p><span class="user-mention" data-user-id="116118">@Matthew Jasper</span> I expect errors for both — I'm not sure why the second one works with NLL, that's curious</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Universes/near/154578285" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Universes.html#154578285">(Jan 07 2019 at 15:49)</a>:</h4>
<p>the reason that I expect an error from the second one:</p>
<p>the <code>T</code> in the impl is bound outside of the <code>fn</code>, so it can't name regions bound on the <code>fn</code> type, but we are trying to equate it with <code>for&lt;'a&gt; fn(&amp;'a u8)</code>. </p>
<p>Reduced: <code>exists&lt;T&gt; { forall&lt;'a&gt; { fn(T) = fn(&amp;'a u8) } }</code></p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Universes/near/155202887" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Matthew Jasper <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Universes.html#155202887">(Jan 15 2019 at 20:47)</a>:</h4>
<p>Finally raised as <a href="https://github.com/rust-lang/rust/issues/57642" target="_blank" title="https://github.com/rust-lang/rust/issues/57642">#57642</a></p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Universes/near/155203059" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> lqd <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Universes.html#155203059">(Jan 15 2019 at 20:49)</a>:</h4>
<p>(I updated the link to not 404)</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Universes/near/155203261" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> lqd <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Universes.html#155203261">(Jan 15 2019 at 20:52)</a>:</h4>
<p><span class="user-mention" data-user-id="116118">@Matthew Jasper</span> do you think the unclear message part of this is a duplicate of <a href="https://github.com/rust-lang/rust/issues/57362" target="_blank" title="https://github.com/rust-lang/rust/issues/57362">#57362</a> or just similar ?</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Universes/near/155203692" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Matthew Jasper <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Universes.html#155203692">(Jan 15 2019 at 20:58)</a>:</h4>
<p>It's pretty similar. They'll probably get solved by the same PR, so long as the PR takes a general approach</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Universes/near/155255615" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Universes.html#155255615">(Jan 16 2019 at 14:08)</a>:</h4>
<p>thanks <span class="user-mention" data-user-id="116118">@Matthew Jasper</span></p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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